The present invention relates to an improved nose assembly for fastener driving tools. More specifically, the present invention relates to improvements in workpiece contact elements for such tools.
Fastener-driving tools are typically powered by pneumatic, combustion, electric, or powder systems, and the present workpiece contact element is contemplated as usable on fastener driving tools regardless of the power system. However, the main focus of the present work contact element will be on its use with combustion-powered framing tools, such as those manufactured by ITW Paslode under the IMPULSE® brand.
Combustion-powered tools, also referred to as combustion nailers, are known in the art, and exemplary tools produced by Illinois Tool Works of Glenview, Ill., also known as IMPULSE® brand tools for use in driving fasteners into workpieces, are described in commonly assigned patents to Nikolich U.S. Pat. Re. No. 32,452, and U.S. Pat. Nos. 4,522,162; 4,483,473; 4,483,474; 4,403,722; 5,197,646; 5,263,439; 5,897,043 and 6,145,724 all of which are incorporated by reference herein.
Such tools generally incorporate a tool housing enclosing a small internal combustion engine. The engine is powered by a canister of pressurized fuel gas called a fuel cell. A battery-powered electronic power control unit produces the spark for ignition, and a fan located in the combustion chamber provides for both efficient combustion within the chamber, and facilitates scavenging, including the exhaust of combustion by-products.
The engine includes a reciprocating piston having an elongate, rigid driver blade reciprocating inside a cylinder having an attached nosepiece. Fasteners are fed to the nosepiece from a magazine where they are held in a properly positioned orientation for receiving the impact of the driver blade.
Generally, when a user wishes to actuate the tool, they place the workpiece contact element against the workpiece and depress the tool housing relative to the workpiece contact element. Through the connection of the workpiece contact element to a sliding valve sleeve in the combustion engine, this action closes the combustion chamber. In a sequential mode of operation, once the user pulls the trigger, the combustion is initiated. Upon ignition of a gas/air mixture in the combustion chamber, the piston/driver blade is driven down the sleeve or cylinder. A leading end of the driver blade engages a fastener and drives it along a channel defined by the nosepiece into a workpiece. The piston and driver are then returned to the original, pre-firing position by differential gas pressures.
However, due certain awkward application angles, the workpiece contact element may not be able to properly grip the workpiece, which may prevent proper tool actuation. In addition, in some tool application angles, a user may not be able to hold the tool in place, causing the fastener to propel into the workpiece at an unsatisfactory angle, or preventing the fastener from properly penetrating the workpiece.
To address this problem, fastener-driving tools have been developed where the workpiece contact element includes teeth constructed and arranged for gripping the workpiece during actuation for preventing movement of the tool. Specifically, pneumatic-powered fastener driving tools typically have a cylindrical or round nose with teeth about the periphery. This arrangement facilitates fastener driving in many angular orientations and in tight spaces. Generally, in combustion tools, the workpiece contact element is rectangular to slidingly engage a similarly shaped nosepiece, and teeth are located at the front and sides of the element. The teeth are generally configured for engaging the workpiece when a longitudinal axis of the tool is arranged perpendicular or at an angle to the workpiece, and the magazine is oriented at an inclined angle to the workpiece.
Although this configuration is acceptable in some instances, combustion powered nailers used in framing, also called framing tools, are frequently used to perform “toenailing.” During toenailing, a fastener is propelled at an angle to join two perpendicularly arranged workpieces such as wooden studs. This application is contrasted with typical tool orientation, where the tool is usually perpendicular to the workpiece. However, during toenailing, the tool must be positioned at an angle such that the magazine is arranged generally parallel to the workpiece. In this orientation, it can be difficult for many current combustion tools to actuate, because the workpiece contact element teeth are not properly oriented to engage the workpiece. If the workpiece contact element does not positively engage the workpiece, the power source valve sleeve cannot close the combustion chamber. Thus, ignition will be prevented.
Accordingly, there is a need for an improved workpiece contact element for a combustion nailer configured for enabling actuation of the tool when the magazine is arranged generally parallel to the workpiece. There is also a need for an improved combustion nailer workpiece contact element which more positively engages or grips the workpiece.